Homeowners can save themselves quite a bit of money performing simple repairs like this one. New mower blades tend to be reasonably priced, and mower blade replacements usually only require the use of a wrench.

Mower blade mounting designs vary, but the basic steps are usually the same. Most mowers have use a very simple blade mounting design like the mower we use below as an example .

Step 1: Set the Mower on Its Side

Always set the mower on the side that does not have a carburetor so that the mower's fuel does not leak out.

Make sure the gas and oil caps are screwed on tightly before tipping the mower.

Step 2: Remove the Fasteners Holding the Mower Blade On

This just means removing one nut on our example mower, and this is usually the case for most mower models.

Use one hand to steady the blade when first loosening the nut.

Step 3: Remove the Old Mower Blade

Step 4: Install the New Blade

Most mower designs will not allow the mower blade to be installed with the wrong side down.

Our example mower blade and its retaining plate are shaped so that the blade can only be installed in the correct position

It is possible to incorrectly install mower blades on some mowers. And it's always possible to install a blade too loosely.

Vibration and poor lawn cutting will quickly make a poor mower blade installation noticeable. A quick adjustment is all it takes to get back to work in the event of an incorrect installation.

Step 5: Conclusion

The surprising thing about this repair might be how easy it is, especially since many lawn mower owners do not take the opportunity to save money on tool repairs by doing them at home.

If your mower blade is dull, damaged, or heavily worn, visit our eReplacementParts.com Lawn Mower Blades page to start your search for a compatible match and get started with this fast and easy repair.

If you've never done this task before, this is NOT the Instructable to follow. You're much better off following drezac's instructions in his comments below. Otherwise, you're liable to get some bruises or cuts or worse.

Besides not mentioning the horrific safety item of not removing the spark plug wire first to avoid an accidental starting of the lawnmower with your hands around the blade, just look at that photo with the bare hands holding the blade between one's fingertips. That's just asking for trouble. Also, note the hand on the ratchet wrench - nobody holds a ratchet wrench like that in a situation when a good amount of force must be applied.

BTW, with the underside of a mower that dirty with crusted-on grass and gunk, you just know that that mower blade hasn't been serviced in a long while and is not going to come off with a few simple turns of the ratchet.

Also, check out that last photo - NOW the guy is going to put on a protective glove. (Maybe the glove in this photo is necessary to hide the fingers lost in the execution of the previous Instructable steps....)

Drain your gas first. You can siphon it to make it easiest. Don't worry about a little left in the tank. The bigger concern is tilting the mower with the MUFFLER in the air. Otherwise, you will likely drain oil into the muffler and it will smoke terribly until it all burns out. There isn't an easy way to clean oil out of a muffler, especially if the bolts/threads are rusted.

Furthermore, use a breaker bar or a ratchet with a pipe if you don't have an impact gun handy. A wrench is much more likely to slip off and leave you with scrapes and cuts. You can use a C-clamp or anything else to stop the blade from rotating so you can use both hands to steady the tools.

If you buy parts from your local mower shop, you'll be more likely to get the right part and have it that day. You can take in your old blade or just the model numbers from the frame if you don't know the part number.

If you're looking to sharpen your blade, make sure to check the balance. You can buy a blade balancer or you can use a screwdriver with a round shaft passing through the center hole of the blade. If one side keeps dipping down, grind more off of that side until it balances.

THANK YOU! Thank you for easy to understand instructions plus pictures. My boyfriend AND my adult son BOTH told me that I COULD/SHOULD NEVER set my lawn mower on it's side - EVER. I told them it was safe if I put it on the proper side - but they said there was NO "proper" side. They agreed to settle on whatever YOU said, therefore I WON and was able to change my blade without any more interruption! Thank You Again!

my great uncle would not agree with you, neither would his two missing fingers, you can get the blade to spin around once with the same amount of force it has when it is running by simply building up compression in the chamber, that is why they tell you to take the spark plug out to remove the chance of compression, also, all you have to do is turn the fly wheel to create a spark, and what little fuel is in the chamber will ignite and give that extra umph to kick that blade around. Please for the sake of your fingers, always remove the spark plug

I use a pneumatic impact gun to remove mower blades. Bang and it is done. If I had to do it with hand tools the last tool I'd pick would be a ratchet. I'd use either a breaker bar or the combination wrench like what you're putting the blade back on with. A few taps with a mallet or scrap of wood on the end of the tool in the direction you want to spin would loosen the nut fast.

I get dozens of sharpenings out of a blade too not just a few like you said. I sharpen my tractor blades every other cut and only replace them every other year.